The sleepless nights associated with a new baby are most likely to be suffered by mothers, while fathers sleep like a baby.

A survey has shown two thirds of new fathers fail to wake when the baby cries in the night.

Eight out of 10 mothers say lack of sleep puts their relationship under "immense strain", and 81% say it causes rows.

The older the mother, the worse the problem.

Parents-to-be have no concept of how the lack of sleep a baby brings will devastate their lives

Dani Our,Mother and Baby magazine

The survey of 2,000 new mothers from Mother and Baby magazine shows 90% of mums over 34 say their relationship has been affected.

Older mothers also told the survey they were tearful or forgetful.

And 60% of all mothers whose babies were 18 months old or under said that lack of sleep had put them off sex completely.

Gender gap

The gender gap is highlighted by the amount of sleep new parents have.

New mothers average four hours a night, sometimes less for those who are breastfeeding.

But two-thirds of new fathers sleep through and 22% never get up.

Mothers are also the ones who spend time settling their baby to sleep, which on average takes 25 minutes.

They are then disturbed up to three times a night, to feed, change or comfort their baby.

Single mothers seem to be least affected by sleep deprivation, with just 41% saying it made them irritable, compared to an average of 55%.

Mothers who work have extra problems.

Eighty-three per cent of those who combine motherhood with career say the lack of sleep affects their performance at work. Again, things are worse for those over 34.

And 88% who go back to work say they feel "fed up, exhausted and pulled in too many directions".

But two thirds of fathers also say they are adversely affected.

And around two-thirds of men and women say their bosses do not understand the problem.

Parents resort to all kinds of measures in a bid to get their new son or daughter off to sleep.

Three-quarters put the baby in their own bed, 33% give the baby a dummy and two out of 10 put the baby into its buggy and take it out for a walk or a drive in an attempt to lull the child to sleep.

Mobiles, lullaby tapes or even "womb music" are some of the more unusual methods parents who are desperate to get their baby to sleep use.

Sleep deprivation 'devastating'

Dani Zur, editor of Mother and Baby magazine said: "The trend nowadays is to have children at a later age and although there are many positive points such as greater financial security, older mums don't have the same energy levels as those in their 20s.

"Parents-to-be have no concept of how the lack of sleep a baby brings will devastate their lives.

"If you're getting less than four hours sleep a night, it's going to make you bad tempered and you'll probably take your anger out on your partner. You'll also feel irritated with your baby and frequently tearful."

"The fresh-faced image of famous older mums like Madonna and Cherie Blair doesn't usually show the entourage of helpers that follow them around."

Professor Neil Douglas, chairman of the British Sleep Foundation, told BBC News Online lack of sleep meant new mums could find it difficult to make decisions and feel depressed, as well as feeling tired because of their sleep deprivation.

He said there was a reason for older mums feeling the effects of sleep deprivation more badly, and for single mums showing lower rates of irritation.

"We know that as people get older, they become more sensitive to sleep deprivation, and one supposes that , on average, single mothers might be younger."